As a result of our work on Spectre, we now know that information leaks may affect all processors that perform speculation…. Since the initial disclosure of three classes of speculative vulnerabilities, all major [CPU] vendors have reported affected products…. This class of flaws are deeper and more widely distributed than perhaps any security flaw in history, affecting billions of CPUs in production across all device classes.
From Ross Mcilroy, Jaroslav Sevcik, Tobias Tebbi, Ben L. Titzer, and Toon Verwaest (all of Google) in Spectre is here to stay; An analysis of side-channels and speculative execution. They continue:» about 300 words